Think about it... if you were a person wanting to see a minority female lead in the MCU, would you be pushing for Shuri (who right now arguably has a 50/50 shot at getting it) or someone like Storm who doesn't even presently exist in the MCU? Which is the more achievable objective?
Whatever your personal feelings on the matter are, objectively speaking it should be fairly obvious to see that right now pushing for Shuri makes sense. They have the best shot they ever had at seeing a female of color as an MCU lead, and perhaps the best shot they ever will have. So of course they are going to take it Objectively speaking they would be fools not to.